Any chance you might bring blank paper to work with you? It might look a bit nicer without the lines. :p

Thanks Jojishi! I only have construction paper/computer paper at home, nothing with lines. And I wanted to keep up the tradition of drawing on lined paper (it seems to help me with proportions and stuff), but you're definitely right that it would look a lot better without the lines. So we'll see what my next one turns out like. Anyways here is another one I drew yesterday at work.

I made a few more in the last couple days. I can tell Tim's shoulders are out of proportion now that I look at it again. I spent about 20-30 minutes on each of these. I'll try to work on the things you guys mentioned. And thanks for the link Elixir. I felt like I learned some stuff from it, but I didn't apply it much in these because the images are small. I'll try making some larger sketches with more detail now that I'm getting the hang of this.

Really nice! I can see the improvement here, try practicing each section of the face separately giving them detail and realism (if realism is what you are going for, I guess it's pretty obvious that you are) and you will have much better result next time! Check this channel's tutorials https://www.youtube.com/user/Sycra, they are a gift from god if you ask me, they have helped me with anatomy, construction and pretty much everything I recommend it a lot, hope to see more portraits soon!